Permanent magnet for electric machines



Feb.l`12 1.924; 1,483,339

c. F. Dui-'Aux PERMANENT MAGNET FOR ELECTRIC 'MACHINES Fi'led Aug. 2s. 1921 I Figi.

Patented Feb. l2, 1924.

UNITED STATES CHARLES FREDERIC DUFAUX, OF GENEVA, SWITZERLAND.

PERMANENT MAGNET FOR ELECTRIC MACHINES.

Application filed August 23, 1921.

To all whom t may concern Be it known that I, CHARLES FREDERIC DUrAUx, a citizen of the Republic of Switzerland, residing at Geneva, Switzerland, have invented certain new and useful Im. provenients in Permanent Magnets for Electric Machines, of which the following is a specification.

During a long time permanent horse-shoe magnets have been employed with magnetoelectric machines. These magnets have two inconvenient factors: First of all, if it is desired to have the air-gap of the magnetoarmature to remain constant, it is necessary to provide the electro-magnet with polar pieces, which render it heavier and complicate its construction. Furthermore, if the magnet is to be placed inside a cylindrical casing, this cannot be done without the loss of much space and the use of complicated devices for fixing it properly in position.

To obviate these inconveniences7 already some years ago the construction of permanent bell-magnets has been devised. These have the shape of a sleeve, slit according to two or several of its generatrixes, in order to separate the poles. The right section of the magnets being circular, it is not necessary to provide the latter with polar pieces, and they can be very easily fixed inside a cylindrical casing, however, their construction is delicate and expensive. It is, in fact, necessary to make a sleeve of steel, which means complicated work, and to make longitudinal fissures in said sleeve, requiring also a long and difficult working process.

The magnet which is the object of this invention has, with respect to the horseshoe magnets, the same advantages as the bell-magnets, and is easier to be manufactured than the latter type.

The drawing represents a descriptive, but not restrictive example of a magneto for lighting purposes, adapted to be fixed on to a bicycle, its inductor comprising two identical forms of the magnet, given by Way of example only, which comprises the obJect of this invention.

Fig. 1 represents an axial section of the magneto. Fig. 2 shows one of the magnets with the spring holding it firm in position Serial N0. 494,487.

in the magneto. Fig. 3 represents a detail. Fig. if shows a perspective view of the magnets.

- The represented magneto comprises a casing, constructed with a cylindrical jacket a3 and two fianges al and 032. The armature o can rotate freely in said casing. The shaft of the armature extends through the flange a2 and carries outside the latter a pulley c. This pulley has to come in contact with the pneumatic tire of the front Wheel of the bicycle, so as to actuate the rotor b at the same time as said front wheel rotates. The other extremity d2 of the shaft of the rotor revolves inside a hollow cylinder, conductor, insulated from the bottom al through which it passes, and whereon a terminal Z3 of the machine is fixed.

The armature of the magneto consists in the two permanent magnets e; each one of these is constructed of a steel plate, in the middle of which is made a rectilinear fissure e1 for the purpose of separating the poles, and which plate is afterwards bent, in such a way as to form, in a right section, the form of an arc of a circle of about 180 (see Fig. 2, bottom). The flange al has a shoulder f1 against which comes to butt the inferior extremity of the two magnets e; the superior extremity of these magnets presses against an annular projecting piece f made in the fiange a2. An elastic, slit ring /L (see Figs. 1 and 3) fixed inside the magnets, holds the latter in position, well. as the two springs g (see Figs. l and 2), the middle part of which presses against the walls of the slit c1, Whilst the extremities press against the jacket a3. lc is a support, represented in a scheme, permitting the fixing of the magneto to the frame of the bicycle.

The magnet can be very easily manufactured, since it suflices to make a fissure c1 in a steel plate, and afterwards to bend the latter according to a half-cylinder. It is not necessary to provide said magnet with polar pieces in order to create a constant air-gap of the rotor. It is also most easy to fix the two magnets inside the cylindrical casing, solely b means of a shoulder f1 of one of the anges, of a projecting piece f on the other fiange, and of the three elastic pieces 7L and g. The two magnets composed of at least one Steel-plate bent can be very easily taken off zuid replaced iii according to u cylindrical surface embrac- 10 position. ing au :ingle of at least 1800, :1nd provided,

Having thus fullyv described the iiive1iat one of its extrcxiiities? with :i slit Sepri- 5 tion, what is claimed as new zuid desired to rating both poles.

be secured by Letters Patent is: In testimony whereof I have affixed my A permanent magnet for electric masignature.

chilies, characterized by the fact that it is CHARLES FREDERIC DUFAUX. 

